Run for Your Life Flashcards
Label the Diagram
Describe the role of tendons.
Attach muscle to bones. Enable muscles to power joint movement. Not elastic. Made of white fibrous tissue - bundles of collagen fibres so strong.
Describe the role of ligaments.
Holds the position of bones and controls and restricts movement in the joint. Made of yellow elastic tissue and collagen which gives both strength and elasticity and flexibility. Connects bone to bone.
Describe the role of cartilage.
Cartilage protects bones within joints. Hard but flexible. Elastic and able to withstand compressive forces. Made of cells called chondrocytes within an organic matrix of collagen fibres. Very good shock absorber. 2 types: hyaline cartilage and white fibrous cartilage.
Describe the role of bone.
Supports the body structure and protect vital organs, strong and hard.
Bone cells embedded in a matrix of collagen fibres and calcium salts is light. Very strong under compression forces.
Describe the role of synovial fluid.
Acts as lubricant
Describe how a pair of antagonistic muscles work to move a joint.
The pair of muscles create opposite forces. When one relaxes (stretches), the other contracts (shortens).
What are the extensor and flexor muscles?
- Extensor muscle: the muscle which contracts to extend the joint.
- Flexor muscles: The muscle which contracts to flex/ bend the joint/ limb.
What are the 3 main types of muscle?
- Smooth muscle
- Cardiac muscle
- Striated, Voluntary or Skeletal Muscle
Describe smooth muscle.
Under the control of the involuntary nervous system. Causes slow contractions of many internal organs, i.e. arteries, intestine. Long and spindle shaped cells, each with their own nucleus. No striations/stripes (parallel groves). Contractions are slow & long lasting, and the fibres fatigue very slowly.
Describe cardiac muscle.
Only found in the heart. Striated/striped muscle. Interconnected fibres to ensure a co-ordinated wave of contraction. Contracts spontaneously (myogenic). Does not fatigue. Capable of short contractions over a long time period (your whole life).
Describe Striated, Voluntary or Skeletal Muscle.
Muscle attached to the skeleton & involved in locomotion.
Under the control of the voluntary nervous system. It contracts rapidly, but fatigues quickly. Capable of strong contractions.
Describe the muscle tissue.
Muscle is made up of bundles of muscle fibres, surrounded by connective tissue. Each muscle fibre is one cell which is multinucleate and striated. Inside the muscle fibre cell are numerous myofibrils. Each myofibril is composed of repeated contractile units called sarcomeres. The two types of protein within these are actin and myosin.
Describe what happens when muscle contracts.
Contractions are brought about by co-ordinated sliding of the protein filaments over each other in the sarcomere. The actin moves between the myosin. This shortens the length of the sarcomere, and hence the length of the muscle.
Why do muscles appear striped (striated) under the microscope?
The actin and myosin overlap. Where actin filaments occur on their own, there is a light band on the sarcomere. Where myosin filaments occur on their own, there is an intermediate-coloured band. Where both actin and myosin filaments occur, there is a dark band.
Define sarcoplasm.
The cytoplasm of a muscle cell.
Describe the sequence of events that occurs at the neuromuscular junction.
A nerve impulse arrives from a motor neurone. Acetylcholine is released from the end of the neurone. Acetylcholine results in the release of calcium ions (Ca2+) from the sarcoplasmic reticulum. Ca2+ diffuse into the sarcoplasm surrounding the myofibrils.
Describe the Sliding filament theory.
Nerve impulses at a neuromuscular junction release Ca2+ ions from the sarcoplasmic reticulum. These diffuse through the sarcomere. Ca2+ ions attach to troponin on the actin causing tropomyosin to shift position and expose myosin binding sites. Myosin heads bind with binding sites and form cross bridges. This releases ADP and Pi. Myosin changes shape and the myosin head moves forward. Actin moves over the myosin.
ATP binds to myosin causing the head to detach. ATPase hydrolyses ATP to ADP and Pi changing the shape of the myosin head and returning the myosin head to it’s previous position.
Describe what happens when the muscle relaxes.
The muscle is no longer stimulated by the motor neurone. Ca2+ is pumped back into the sarcoplasmic reticulum by active transport. This requires ATP. The troponin moves back to its original position and the tropomyosin moves to back to cover and block the myosin binding sites on the actin.
Describe what happens to muscles in rigor mortis.
After death, ATP production stops. With an absence of ATP, the myosin heads will remain attached to the actin (the cross-bridges stay intact). The muscle is unable to relax and remains ridged. The cross-bridges are only broken when the muscle fibres start decomposing.
Describe the role of calcium ions in the contraction of skeletal muscles.
- Calcium ions released in response to nervous stimulation of the muscle set up contraction of the sarcomeres
- Calcium ions bind to troponin changing the shape of the molecule
- This change in shape pulls the tropomyosin away from the myosin binding sites on the actin molecules exposing them
- The myosin heads now bind, setting up the contraction
- Calcium ions are also needed for the action of the ATPase enzyme in the myosin heads, which enables the heads to return to their original resting position
Explain why the presence of ATP and it’s hydrolysed form are so important for the contraction of striated muscle.
- The ATP binds to the myosin head, and the release of energy when it is hydrolysed allows the head to return to the resting position
- The bonding of ADP and Pi results in changes in the shape of the myosin head so it can bind to the actin binding site
- The release of the ADP and Pi results in another shape change which results in the bending of the myosin head causing the actin to slide over the myosin
- ATP is also needed as the energy supply for the calcium pump which returns calcium ions to the sarcoplasmic reticulum, ending the contraction.
Write the overall word and balanced chemical equation for respiration.
Glucose + Oxygen –> Carbon Dioxide + Water + energy
C6H12O6 + 6O2 –> 6CO2 + 6H2O + 38 ATP
Draw a mitochondrion